node: add MessageID to observation messages

This allows us to associate an observation from the log
for messages that the local node did not observe.

Change-Id: I6ece7bfe3e6b878bdb7ee4ac03c81cb424a329b3

node/pkg/processor/broadcast.go

@@ -33,6 +33,7 @@ func (p *Processor) broadcastSignature(v *vaa.VAA, signature []byte, txhash []by
 		Hash:      digest.Bytes(),
 		Signature: signature,
 		TxHash:    txhash,
+		MessageId: v.MessageID(),
 	}
 
 	w := gossipv1.GossipMessage{Message: &gossipv1.GossipMessage_SignedObservation{SignedObservation: &obsv}}

node/pkg/processor/observation.go

@@ -59,6 +59,7 @@ func (p *Processor) handleObservation(ctx context.Context, m *gossipv1.SignedObs
 		zap.String("addr", hex.EncodeToString(m.Addr)),
 		zap.String("txhash", hex.EncodeToString(m.TxHash)),
 		zap.String("txhash_b58", base58.Encode(m.TxHash)),
+		zap.String("message_id", m.MessageId),
 	)
 
 	observationsReceivedTotal.Inc()

proto/gossip/v1/gossip.proto

@@ -81,6 +81,9 @@ message SignedObservation {
   // Transaction hash this observation was made from.
   // Optional, included for observability.
   bytes tx_hash = 4;
+  // Message ID (chain/emitter/seq) for this observation.
+  // Optional, included for observability.
+  string message_id = 5;
 }
 
 // A SignedVAAWithQuorum message is sent by nodes whenever one of the VAAs they observed